just sit it on top of the screen. fluorescent tubes emit much less heat that incandescent bulbs anyway, so they are actually safer than the basking spots to have sitting directly upon the screen. furthermore, glass absorbs UV, so if you have a UV bulb shining through the glass you might as well have a normal bulb.
before i switched to MVBs, I had the 8.0 UV strip directly on my screen. you should also bear in mind that screen tops can absorb up to 50% of UV light, and the strips are only good for 6-10" from source, so unless the basking site is close to it, your beardie may not benefit from the UV. You may want to mount the UV strip inside the tank if thats possible, but really on top of the screen is fine, thats what most of us do / have done.
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Ross
0.1 Bearded Dragon (Fuego, spent the last 10 months thinking she was a he!)
2.1 Roommates (require more cleaning up after than the dragon)